CN103973388B - Optical line terminal, optical network unit, optical communication system and correlation method - Google Patents
Optical line terminal, optical network unit, optical communication system and correlation method Download PDFInfo
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Abstract
ONU in existing TWDM PON uses tunable laser, and cost is high.The invention provides optical line terminal, optical network unit, optical communication system and correlation method, wherein, the optical line terminal includes dual wavelength maker (2), respectively for the seed photo-signal for the multiple different wave lengths being re-used, the first optical signal of different frequency corresponding with the seed photo-signal is generated as first group of optical signal and the second optical signal and is used as second group of optical signal；Multiple Corticofugal Modulation of Somatosensory modules (7), each first optical signal corresponded respectively in first group of optical signal, downlink information is modulated on each first optical signal；Coupler (8), second group of optical signal and first group of optical signal for having been modulated downlink information are coupled, and exports.And on optical network unit, including downlink reception module, corresponding first optical signal is detected, downlink information is obtained；And up modulation module, uplink information is modulated on corresponding second optical signal and exported.
Description
Technical field
The present invention relates to optical-fiber network, more particularly to the wavelength division multiplexed optical network based on EPON.
Background technology
With the extensive use of high-level multimedia, such as 3D TVs, Telemedicine, game on line, interdynamic video
The exploitation of the applications such as habit, has huge growth to the demand of bandwidth.PON2 (NG-PON2) of future generation is used as Long Term Evolution
PON solutions, just as a focus subject under discussion, by portion of international telecommunication union telecommunication (ITU-T) and FSAN (Full
Service Access Network, abbreviation FSAN) discussed.It is bigger that most operator wishes that NG-PON2 can be provided
Bandwidth, higher splitting ratio (split ratio), longer transmission range and more preferable access capability.At present, ITU-T
NG-PON2 demand is finally being determined with FSAN, available bandwidth is increased into 40Gb/s speed.
In the technical scheme proposed, TWDM-PON is considered as to NG-PON2 by nearest FSAN meetings
Primary solutions, wherein, 4 10G-PON (XG-PON) be stacked and with 1: 64 splitting ratio, this can be obtained
Obtain down direction 40Gbps and up direction 10GGbps rate of polymerization.In single wavelength, TWDM-PON has reused XG-PON
Descending multiplexing and multi-upstream access technology, time slot granularity, multicast capability and Bandwidth sharing mechanism.
But, in TWDM-PON, ONU emitters must have the ability to modulate uplink information into four upstream wavelengths
On any one wavelength.ONU receivers must also have the ability to detecting down on any one wavelength in four downstream wavelengths
Row information.Therefore, the adjustable ONU for designing low cost becomes a crucial technical problem.
At present, Wavelength tunable technology is the existing preferred plan for being used to realize colorless ONU, wherein, a tunable optical filter
Ripple device is used for downstream signal wavelengths selectivity, and tunable laser is used for upward signal emitter, as shown in Figure 1.Specifically
Say, in down direction, in optical line terminal OLT, after four downstream wavelengths are converged by grating AWG (left part in OLT), by annular
Device is exported.The optical splitter being transferred to via optical fiber in remote node RN, remote node RN divides be re-used four downstream wavelengths
For n roads, signal of each of which road all with four downstream wavelengths.The multiplexed signals all the way of optical splitter output reaches optical-fiber network list
First ONU1, the optical network unit ONU 1 corresponds to wavelength X1.Its AWG and tunable optical filter are by corresponding to the wavelength X of the ONU11
Signal selected from the signal of four downstream wavelengths of multiplexing, and be supplied to receiver Rx to be detected.And in up direction,
Tunable laser in ONU1, which will be exported, has been modulated the wavelength of upward signal for λ '1Upward signal.The upward signal passes through
AWG in ONU is provided to RN.The upward signal of each ONU different wave lengths provided is multiplexed together by the optical splitter in RN,
OLT is sent back by optical fiber.Circulator in OLT sends upward signal the AWG, the AWG for being responsible for selecting each upstream wavelength
Each upstream wavelength is separated and corresponding uplink receiver Rx (OLT middle and lower parts) is respectively supplied to.
But, tunable laser is very expensive equipment.Particularly, when NG-PON2 needs to support point more than 1: 64
, it is necessary at least 64 ONU users during light ratio, then the totle drilling cost of tunable laser will be into greatly increasing.Due to tunable laser
It is costly, and the high cost is linearly increasing with ONU quantity, limits the deployment and implementation of TWDM-PON systems.
Accordingly, it would be desirable to design the adjustable ONU of low cost in TWDM-PON systems.
The content of the invention
This solution is focused on designing the inexpensive ONU in TWDM-PON systems, while keeping traditional ODN
(optical distributed network).The basic conception of the present invention includes any one following in some：
1. the new dual wavelength generation of Mach-Zehnder (Mach-Zehnder) modulator design based on common single driving
Device, such as 4 light sources can produce 8 independent wavelength.
2. 8 wavelength are divided into quantity identical two using the Mach-Zehnder delay interferometer (MZDI) of low cost
Point, a part is used as seed light and is an externally injected among common commercial FP-LD to be used for descending optical signal to produce,
Another part is not modulated and is directly transmitted to ONU, as the light carrier of upward signal, to be modulated by upward signal.
3. remote node has optical splitter, identical with the remote node in traditional ODN frameworks so that the invention is to tradition
ODN frameworks have compatibility.
4. in ONU, required wavelength is selected based on single adjustable smooth selecting module, using common photoreceiver, with
And uplink communication is carried out using common ROSA, the adjustable ONU of low cost is realized, without being provided using tunable laser
Optical signal is to carry out upward signal modulation.
According to first basic aspect of the present invention there is provided a kind of optical line terminal, including such as lower component：
- the first array waveguide grating, is connected with the dual wavelength maker, the kind for receiving multiple different wave lengths respectively
Sub-light signal, is converged, and is supplied to the dual wavelength maker；
- dual wavelength maker, the seed photo-signal for receiving the multiple different wave lengths being re-used, and respectively for various
Sub-light signal, the first optical signal for generating different frequency corresponding with the seed photo-signal is used as first group of optical signal and the second light
Signal is used as second group of optical signal；
- light separator, for will be separated together corresponding to the first of each seed photo-signal group of optical signal, and will correspond to
Second group of optical signal separation of each seed photo-signal is together；
- optical selector, for selecting each first optical signal respectively from the first group of optical signal isolated；
- multiple Corticofugal Modulation of Somatosensory modules, correspond respectively to each first optical signal, and downlink information is modulated into first light believes
On number, and feed back to the optical selector；
Each first optical signal for being modulated with downlink information is multiplexed with first group of optical signal by the optical selector；
- coupler, for by the second group of optical signal isolated and be re-used, the institute of having been modulated downlink information
State first group of optical signal to be coupled, and export.
Correspondingly, according to second basic aspect of the invention, present invention also offers a kind of optical network unit, including such as
Lower component：
- light selecting module, for receiving optical signal, therefrom selects the different frequency corresponding to same seed photo-signal
The second optical signal in the first optical signal and second group of optical signal in first group of optical signal, and first and second light is believed
It is number separated from each other, wherein, first optical signal has been modulated downlink information；
- downlink reception module, for being detected to first optical signal being separated, obtains the descending letter
Breath；
- up modulation module, for second optical signal for being modulated to be separated by uplink information, and will be adjusted
Second optical signal for having made uplink information is reflected back the smooth selecting module to export.
From the angle of system, the invention provides a kind of optical communication system, including：
- described according to the first aspect of the invention optical line terminal；
- optical branching device, is connected with the optical line terminal；
- multiple optical network units according to second aspect of the invention, are connected with the optical branching device respectively；
The downlink optical signal branch that the optical branching device provides the optical line terminal is to each optical network unit.
In the above of the present invention, by producing adjustable upstream wavelength in the olt and being supplied to ONU, by system
Complexity is transferred in OLT, and wavelength management is eliminated in ONU, it is to avoid use tunable laser, effectively reduce ONU into
This.Also, correspondingly the substantial increase to wavelength or ONU provides scalability, i.e., when needing increase wavelength, improve OLT
The increase of up-downgoing wavelength can be realized simultaneously；Thus when needing increase ONU, the surge of system cost is not resulted in.
According to one preferred embodiment, the dual wavelength maker includes input port, tie point in parallel, the
The seed photo-signal of input is divided into described first by two branch roads, and output port, the input port by certain splitting ratio
Road and second branch road, also, be stacked adduction by the signal of the tie point and the second branch road and pass through the output end
Mouth output,
Wherein, the tie point includes a Mach-Zehnder modulator, and the Mach-Zehnder modulator receives certain
The bias voltage of the radiofrequency signal of frequency and certain amplitude so that the Mach-Zehnder modulator export the seed photo-signal with
And be the second order sideband signals of twice of certain frequency with the seed photo-signal frequency interval；
Second branch road includes one section of waveguide, and with a phase-modulator, the phase-modulator will be adjusted
The seed photo-signal on second branch road so that phase is reverse；
The reverse seed photo-signal of the tie point and second branch road are provided respectively, phase is at least partly
Ground is cancelled out each other, and the second order sideband signals are exported as first and second optical signal by the output port.
This embodiment offers a kind of concrete implementation mode of the dual wavelength maker.
According to a further embodiment, the splitting ratio of the tie point and second branch road is 80: 20, and the horse
Conspicuous-zehnder modulators the are exported, seed photo-signal is identical with the amplitude of the second order sideband signals.Preferably
In, dual wavelength maker can offset seed photo-signal in a low energy level, it is ensured that the power of the second order sideband of output
Meet modulation and transmission demand.
According to a further embodiment, the frequency of the radiofrequency signal is 12.5GHz.12.5GHz radio frequency letter
Number frequency can produce each downlink optical signal that each uplink optical signal and frequency interval that frequency interval is 100GHz are 100GHz,
Meet TWDM-PON demand.
According to one preferred embodiment, the light separator includes：
- Mach-Zehnder delay interferometer, with an input port and two output ends, wherein,
First output end is coupled to the optical selector, and the peak of the transmission spectrum of first output end matches each first respectively
The wavelength of optical signal；
Second output end is coupled to the coupler, and the peak of the transmission spectrum of second output end is matched and each second respectively
The wavelength of optical signal.
This embodiment offers a kind of concrete implementation mode of the light separator.
According to one preferred embodiment, the Corticofugal Modulation of Somatosensory module includes fabry-Perot type laser, the light choosing
Device is selected including the second array waveguide grating, and the light separator, second array waveguide grating and the coupler it
Between be connected with：
- first annular device, each first optical signal that the light separator is provided, being separated is supplied to described second
Array waveguide grating, and by it is being multiplexed by second array waveguide grating, be reflected back be modulated with each of downlink information
First optical signal is supplied to the coupler.
In this embodiment, the relatively low fabry-Perot type laser of use cost completes modulation function, and cost is relatively low.
According to one preferred embodiment, it is also associated between the dual wavelength maker and the light separator：
Depolarizer, the polarization state for removing each first and second optical signal.
This preferred embodiment in, because depolarizer eliminates the polarization dependence of traditional injecting lock mould, so FP-
LD can be used for the downlink data that modulation data rate is up to 10Gb/s, improve communication performance..
According to one preferred embodiment, the optical line terminal also includes：
- uplink receiving module；
- the second circulator, is connected to the coupler, the output port of the optical line terminal and the uplink receiving mould
Block, is supplied to the output port to export the coupler coupled signal, and the upward signal that the output port is received is provided
To the uplink receiving module.
This embodiment offers the functional structure for uplink receiving part.
In ONU, it is preferable that the smooth selecting module includes：
- tunable optical filter, corresponds to together for being filtered out from the first group of optical signal and second group of optical signal that are received
First and second optical signal of one seed photo-signal,
The tunable optical filter can be conditioned to be matched from any one in multiple different seed photo-signals.
Support this embodiment offers ONU to multi-wavelength.
Preferably, the up modulation module is also by second optical signal amplification, and the up modulation module includes anti-
Penetrate formula semiconductor optical amplifier.
Because OLT provides uplink optical signal, so ONU can be using cost very low reflective semiconductor optical amplifier
(RSOA) uplink optical signal is amplified and modulated, reduce ONU costs.
From the angle of method, the fourth aspect of the invention provides a kind of side of the transmission downstream signal in optic communication
Method, comprises the following steps：
- seed photo-signal for the multiple different wave lengths being re-used is received, and respectively for each seed photo-signal, generate with being somebody's turn to do
First optical signal of the corresponding different wave length of seed photo-signal is used as second group of light as first group of optical signal and the second optical signal
Signal；
- will be separated together, and by corresponding to each seed photo-signal corresponding to the first optical signal of each seed photo-signal
Second optical signal is separated together；
- each first optical signal is selected from the first group of optical signal corresponding to each seed photo-signal isolated；
- each first optical signal is corresponded respectively to, downlink information is modulated on first optical signal；
- each first optical signal for being modulated with downlink information is polymerized to first group of optical signal；
- by the second group of optical signal being separated and be re-used, modulated downlink information described first group
Optical signal is coupled, and is exported.
Correspondingly, the reception downstream signal that the fifth aspect of the invention is provided in a kind of optic communication concurrently serves capable letter
Number method, comprise the following steps：
- optical signal is received, therefrom selection is corresponding in first group of optical signal of the different wave length of same seed photo-signal
The second optical signal in first optical signal and second group of optical signal, and first and second optical signal is separated from each other, its
In, first optical signal has been modulated downlink information；
- first optical signal being separated is detected, obtain the downlink information；
- uplink information is modulated on second optical signal that is separated, and the institute that uplink information will have been modulated
The second optical signal is stated to be reflected back the smooth selecting module to export.
Brief description of the drawings
By reading the detailed description made to non-limiting example made with reference to the following drawings, of the invention is other
Feature, objects and advantages will become more apparent：
Fig. 1 is existing TWDM-PON structured flowchart；
Fig. 2 is the structured flowchart of the OLT according to an embodiment of the invention；
Fig. 3 is the schematic diagram of the dual wavelength maker according to an embodiment of the invention；
Fig. 4 is the schematic diagram of the light separator according to an embodiment of the invention；
Fig. 5 is the spectrogram of the input of the transmission spectrum curve and light separator of the light separator shown in Fig. 4；
Fig. 6 is the spectrogram of the output of Fig. 4 light separator；
Fig. 7 shows the optical signal spectrum at multiple light path positions among Fig. 3 OLT；
Fig. 8 is the structured flowchart of the ONU according to an embodiment of the invention；
Fig. 9 is the transmission spectrum curve of the light selecting module in Fig. 8；
Figure 10 shows the optical signal spectrum at multiple light path positions among Fig. 8 ONU.
Embodiment
As shown in Fig. 2 the invention provides a kind of optical line terminal OLT, including such as lower component：
- the first array waveguide grating 11, the seed photo-signal λ for receiving multiple different wave lengths respectively1, λ2, λ3, λ4, will
It is converged, and is supplied to dual wavelength maker 12；
- dual wavelength maker 12, the seed photo-signal λ for receiving the multiple different wave lengths being re-used1, λ2, λ3, λ4, and
Respectively for each seed photo-signal, the first optical signal for generating different frequency corresponding with the seed photo-signal is used as first group of light
Signal and the second optical signal are used as second group of optical signal；
- light separator 14, for isolating first group of optical signal c and second group of optical signal d, respectively from two output end
Mouth output；
- optical selector 16, for selecting each first optical signal respectively from the first group of optical signal c isolated；
- multiple Corticofugal Modulation of Somatosensory modules 17 (one is only shown in Fig. 2), correspond respectively to each first optical signal, by descending letter
Breath is modulated on first optical signal, and feeds back to the optical selector 16；
Each first optical signal for being modulated with downlink information is multiplexed together by the optical selector 16 to be believed as first group of light
Number e；
- coupler 18, for by isolate second group of optical signal d and be re-used, modulated downlink information the
One group of optical signal e is coupled, and exports.
As shown in figure 8, present invention also offers a kind of optical network unit ONU, including such as lower component：
- light selecting module 21, for receiving optical signal, therefrom selects the different frequency corresponding to same seed photo-signal
The first and second optical signals, it is and first and second optical signal is separated from each other, wherein, first optical signal is adjusted
Downlink information is made；
- downlink reception module 22, for being detected to first optical signal being separated, obtains the descending letter
Breath；
- up modulation module 23, for second optical signal for being modulated to be separated by uplink information, and will be by
Second optical signal for having modulated uplink information is reflected back the smooth selecting module to export.
Below by more specific description according to the present invention optical line terminal OLT and optical network unit ONU structure with
Function.In following embodiment, to produce the spectrum intervals needed for TWDM-PON as between 100GHz downstream wavelength/frequency spectrum
It is divided into exemplified by 100GHz upstream wavelengths and illustrates, it will be understood that in the case of other required wavelength, the present invention can be done suitably
Change.
4 continuous wave (CW) laser λ with 100GHz spectrum intervals1, λ2, λ3, λ4Light is transfused to as seed photo-signal
Among the OLT of line terminal, and it is gathered together by the first array waveguide grating 11.First array waveguide grating 11 is exported
Optical signal spectrum by Fig. 7 (a) Suo Shi, 4 CW laser are injected among dual wavelength maker 12.
Dual wavelength maker 12 receives the seed photo-signal λ for four different wave lengths being re-used1, λ2, λ3, λ4, and it is right respectively
In each seed photo-signal, the first and second optical signals of different frequency corresponding with the seed photo-signal are generated.
For a kind of implementation of dual wavelength maker, as shown in figure 3, it using a common single driving Mach-
Zehnder modulators (MZM) and a low speed phase-modulator, they are embedded in a Mach-Zehnder delay interferometer respectively
Two branch roads on.Upper branch road is single driving Mach-Zehnder modulator, and lower branch road is one section of optical fiber, and with a low speed
Phase-modulator is used to adjust for the phase difference of two branch signals.Mach-Zehnder modulator has the biasing control of independent control
System, to realize optimal performance and independent external radio frequency input port.
Below with four seed photo-signal λ1, λ2, λ3, λ4In a seed photo-signal exemplified by, it is former to the generation of dual wavelength
Reason is illustrated, it will be understood that dual wavelength maker is that each seed photo-signal generates corresponding first and second optical signal.It is defeated
Light source (the frequency f entereds) it is divided into two parts with certain splitting ratio, such as 20: 80, and it is fed to two branch roads.MZM is by one
Individual electrical clock signal (frequency：fRF) driven, the peak value that the clock signal is offset to transmission curve sentences suppression odd number side band.
The fiber segment of inferior division fully passes through optical carrier.
By adjusting phase-modulator to obtain the phase difference of 180 degree between Liang Ge branches, and control electrical clock signal
Frequency and the amplitude of bias voltage be suitable value, because opposite in phase, amplitude are identical, frequency fsThe signal at place almost may be used
To be cancelled completely.
Based on this design, from single seed laser, the optical signal of dual wavelength can be obtained, composes and is spaced with quadruple
(4fRF), respective frequency is fs+2fRF(can be described as the second optical signal or right channel) and fs-2fRF(can be described as the first optical signal or
Left channel), the first optical signal and the second optical signal can be deemed to be independent laser.The need for considering TWDM-PON, fRFFor
12.5GHz, then the first optical signal and the spectrum intervals of the second optical signal generated by same seed photo-signal is 50GHz；And
Because the spectrum intervals between each seed photo-signal is 100GHz, so the 2x4=8 independent wavelength Xs produced1L, λ1R,
λ2L, λ2R..., λ4L, λ4ROptical signal spectrum such as Fig. 7 (b) shown in, spectrum intervals is 50GHz.Therefore, using four light sources just
8 individual wavelengths alignd with 50GHz ITU-T TWDM-PON grids can be produced.Wherein, the seed light shown in dotted line
Signal λ1, λ2, λ3, λ4Its frequency location is merely to indicate that, actually these seed photo-signals have been cancelled completely or supported
Disappear to very low light intensity level, can not produce in the communications again substantially influences.
It is appreciated that dual wavelength maker can also be realized using other modes, for example with the Mach-once of two cascades
Moral modulator and corresponding control/process signal module.Those of ordinary skill in the art can use other realization sides
Formula realizes the function of dual wavelength maker, and the present invention will not be repeated here.
Next, to be fed by a solution inclined for the 2x4=8 condensed together that is generated the first optical signals and the second optical signal
Device (depolarizer) 13, pseudorandom polarization is changed into by their polarized state (SoP).Because depolarizer be used to disappear
Except the polarization dependence of tradition input locking, and the wavelength of the outside injection from continuous wave has related spy well
Property, so when modulating the first optical signal, the lower line number that modulation rate is up to 10Gb/s can be carried out with the relatively low FP-LD of use cost
According to this is hereinafter also by explanation.It is appreciated that the depolarizer be it is a kind of in order to match FP-LD improve modulation rate it is preferred
Implementation, it is dispensed.
Afterwards, the first optical signal and the second optical signal condensed together is sent to light separator 14, the light separator 14
By corresponding to the first optical signal λ of each seed photo-signal1L, λ2L, λ3L, λ4LSeparation together, and will correspond to each seed photo-signal
The second optical signal λ1R, λ2R, λ3R, λ4RSeparation is together.
In a concrete implementation, a light Mach-Zehnder delay interferometer (MZDI) is used for generated 8 of separation
Individual wavelength signals, form each first optical signal λ1L, λ2L, λ3L, λ4LThe first group of optical signal and each second optical signal λ constituted1R,
λ2R, λ3R, λ4RThe second group of optical signal constituted.Fig. 4 shows the structure of designed Mach-Zehnder delay interferometer, and it has
One input port IN and two output end OUT1 and OUT2, MZDI free spectral range should be 100GHz, and the first He
The spectrum curve skew 50GHz of second output end, therefore, the peak of the first output end OUT1 transmission spectrum matches each first respectively
The wavelength of optical signal, as shown in the spectrum curve of solid line in Fig. 5；The peak of second output end OUT2 transmission spectrum match respectively and
The wavelength and its transmission spectrum of each second optical signal, as shown in the spectrum curve of dotted line in Fig. 5.This MZDI can be used
Commercial ordinary optic fibre makes, and cost is very low, and stability can also be controlled well.First output end of the interferometer
OUT1 exports four left channel (the first optical signal) λ1L, λ2L, λ3L, λ4L, such as shown in Fig. 6 and Fig. 7 (c), the second output end OUT2 is defeated
Go out four right channels (the second optical signal) λ1R, λ2R, λ3R, λ4R, such as shown in Fig. 6 and Fig. 7 (d).
It is appreciated that the light separator there can also be a lot of other implementations, realized for example with grating, this hair
It is bright to repeat no more.
First output end OUT1 of light separator 14 is coupled to the first optical circulator 15, the left letter of first optical circulator four
Road (the first optical signal) λ1L, λ2L, λ3L, λ4LIt is supplied to optical selector 16.Four first light of the optical selector 16 from separation together
Signal λ1L, λ2L, λ3L, λ4LMiddle to select each first optical signal respectively as four independent channels, each wavelength is used as seed light
And be injected into by outside in Corticofugal Modulation of Somatosensory module.Each Corticofugal Modulation of Somatosensory module corresponds respectively to each first optical signal, and Fig. 2 illustrate only
Corresponding to the first optical signal λ1LCorticofugal Modulation of Somatosensory module 17.Downlink information is modulated to the first optical signal by each Corticofugal Modulation of Somatosensory module
On, and feed back to optical selector 16.On implementing, Corticofugal Modulation of Somatosensory module can be realized by common FP-LD.Outside note
Enter the FP-LD after locking to be modulated by downstream signal DL.Respectively to four the first optical signal λ1L, λ2L, λ3L, λ4L, for example, schemed
Signal spectrum shown in 7 (e).
Each first optical signal for being modulated with downlink information is multiplexed together that there is provided to the first circulator by optical multiplexer 16
15.The signal is supplied to coupler 18 by the first circulator 15.
Coupler 18 by separate together, not modulated each second optical signal λ1R, λ2R, λ3R, λ4RWith it is being re-used,
Each first optical signal λ of downlink information is modulated1L, λ2L, λ3L, λ4LIt is coupled, and is exported by the second circulator 19.
OLT is connected to by single optical fiber and gives remote node RN, by not modulated each second optical signal λ of coupling1R,
λ2R, λ3R, λ4RWith it is being re-used, modulated each first optical signal λ of downlink information1L, λ2L, λ3L, λ4LIt is sent to remote node
RN。
At remote node RN, as shown in figure 8, optical splitter be used to the downlink optical signal of arrival being allocated to each ONU.
Therefore embodiments of the present invention support traditional ODN frameworks, can significantly decrease the cost of actual realization.Fig. 8 is in detail
Show to correspond to λ1LAnd λ1RONU, other ONU structure is identical, in order to briefly no longer show.
As shown in figure 8, optical network unit ONU includes：
- light selecting module 81, for receiving optical signal, therefrom selects the different frequency corresponding to same seed photo-signal
The first and second optical signals, it is and the first and second optical signals are separated from each other, wherein, the first optical signal has been modulated descending
Information；
- downlink reception module 82, for being detected to the first optical signal being separated, obtains downlink information；
- up modulation module 83, for the second optical signal for being modulated to be separated by uplink information, and will be modulated
The second optical signal reflected light selecting module of uplink information is to export.
Fig. 9 shows the transmission spectrum curve of light selecting module 81, the peak of the corresponding transmission spectrums of the first output end OUT1
Value corresponds to λ1L, and the peak value of the corresponding transmission spectrums of the second output end OUT2 correspondence λ1R.Then, the first output end OUT1 is downward
Shown in the optical signal that row receiving module 82 is provided such as Figure 10 (a), only the first optical signal λ including having been modulated downstream signal1L。
Optical signal such as Figure 10 (b) that second output end OUT2 is provided to up modulation module 83 is shown, including not modulated any letter
Number continuous wave the second optical signal λ1R。
Preferably, the light selecting module 81 be it is adjustable, it can be conditioned from multiple different seed photo-signals
Any one is matched, i.e., can be adjusted output the first optical signal corresponding with other seed photo-signals and the second optical signal.Can
With understand, this be only preferred embodiment, in the case of the ONU regularly some corresponding seed photo-signal wavelength,
The light selecting module can be fixedly selected out the left channel and right channel of the seed photo-signal wavelength.
82 pairs of downlink reception module is by first optical signal λ1LDetected, obtain downlink information, complete downlink communication.Under
It is well known to one of ordinary skill in the art that what row was received, which implements, be will not be repeated here.
Up modulation module 83 is preferably realized by reflective semiconductor optical amplifier (RSOA).Realized using RSOA
ONU in WDM-PON be determined as it is very promising because it have simultaneously amplification and modulation function.At this
In invention, commercial inexpensive RSOA can be used in modulating 2.5Gb/s upward signal, the small-signal gain with 20dB, 3dB
Protection power output, and very low front end factor reflection (front factor reflectivity).Adjusted in upward signal
Shown in the second channel wavelength such as Figure 10 (c) obtained after system, the modulation wavelength can send back OLT.In the present invention, it is descending and
Upward signal uses different carrier wavelengths, therefore has stronger tolerance to back end reflective (back-reflection), and
Back end reflective is a main deteriorating effect in single fiber feeding scheme.In addition, being reused relative to traditional descending carrier
Scheme, because right channel (the second optical signal) is not modulated continuous light wave, this can effectively improve upstream performance.
Afterwards, in the olt, upward signal is passed to uplink receiving module by the second circulator 19.Uplink receiving module bag
An array waveguide grating 20 and each uplink receiver 21, array waveguide grating 20 are included by the up of each different wave length
Second optical signal is separated, and is respectively supplied to corresponding uplink receiver 21 and is detected.The process is compared with the prior art
It is similar, it will not be repeated here.
In embodiments of the present invention, common inexpensive RSOA is used as adjustable emitter, eliminates in ONU
Expensive tunable laser, therefore ONU cost can be significantly reduced.In order to further reduce OLT cost, in this hair
In bright embodiment, 10Gb/s downstream transmitter can use the outside injection FP-LD by related seed photolocking Lai real
It is existing, save the 10Gb/s of costliness Distributed Feedback Laser.In embodiments of the present invention, the complexity of system is upper to a certain degree
Among OLT, it is necessary to increase an extra dual wavelength generator, depolarizer, the AWG of 100GHz spectrum intervals,
One MZDI, a coupler and a circulator.
Following table lists the PON that the cost and embodiments of the present invention of the TWDM-PON networks of existing scheme composition are constituted
The cost of network compares, and wherein the network includes OLT and 64 ONU.The part being relatively based on all is commercially available
Device.
Table 1
For the TWDM-PON systems of 64 channels, compared with prior art, it is beautiful that the present invention can reduce cost about 8000
Member.Especially, when the quantity increase of ONU user is more, the reduction of system cost is more substantially.
It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in the application can phase
Mutually it is combined.
Certainly, the present invention can also have other various embodiments, ripe in the case of without departing substantially from spirit of the invention and its essence
Various corresponding changes and deformation, but these corresponding changes and deformation can be made according to the present invention by knowing those skilled in the art
The protection domain of appended claims of the invention should all be belonged to.
One of ordinary skill in the art will appreciate that all or part of step in the above method can be instructed by program
Related hardware is completed, and described program can be stored in computer-readable recording medium, such as read-only storage, disk or CD
Deng.Alternatively, all or part of step of above-described embodiment can also use one or more integrated circuits to realize.Accordingly
Each module/unit in ground, above-described embodiment can be realized in the form of hardware, it would however also be possible to employ the shape of software function module
Formula is realized.The present invention is not restricted to the combination of the hardware and software of any particular form.
Claims (10)
1. a kind of optical line terminal, including such as lower component：
- the first array waveguide grating (11), the seed photo-signal for receiving multiple different wave lengths respectively, is converged, and carry
Supply dual wavelength maker；
- dual wavelength maker, the seed photo-signal for receiving the multiple different wave lengths being re-used, and respectively for each seed light
Signal, generates the first and second optical signals of different frequency corresponding with the seed photo-signal；
- light separator, for separating each first optical signal as first group of optical signal and each second optical signal as second group of light
Signal, will be multiplexed respectively from two output port corresponding to the first of each seed photo-signal group of optical signal and second group of optical signal
Output；
- optical selector, for selecting each first optical signal respectively from first group of optical signal；
- multiple Corticofugal Modulation of Somatosensory modules, correspond respectively to each first optical signal, downlink information are modulated into first optical signal
On, and feed back to the optical selector；
Each first optical signal for being modulated with downlink information is multiplexed together and is used as first group of optical signal by the optical selector；
- coupler, for second group of optical signal to be believed with first group of light be re-used, to have been modulated downlink information
Number it is coupled, and exports.
2. optical line terminal according to claim 1, it is characterised in that the dual wavelength maker includes input port,
The seed photo-signal of input is pressed certain splitting ratio by the tie point of parallel connection, the second branch road, and output port, the input port
The tie point and second branch road are divided into, also, is related to by the signal coherence of the tie point and the second branch road
Export afterwards and by the output port, wherein, the tie point includes Mach-Zehnder modulator, and the Mach-once
Moral modulator receives the radiofrequency signal of certain frequency and the bias voltage of certain amplitude so that the Mach-Zehnder modulator is exported
The seed photo-signal and with the seed photo-signal frequency interval be twice of certain frequency second order sideband signals；
Second branch road includes one section of waveguide, and with a phase-modulator, the phase-modulator is used to adjust this
The phase of the seed photo-signal on second branch road so that the phase and former opposite in phase；
The reverse seed photo-signal of the tie point and second branch road are provided respectively, phase is approximate completely mutually
Offset, and the second order sideband signals are exported as first and second optical signal by the output port.
3. optical line terminal according to claim 2, it is characterised in that the tie point and the splitting ratio of second branch road
For 80:20, the frequency of the radiofrequency signal is 12.5GHz, and the Mach-Zehnder modulator is exporting, the seed photo-signal
It is identical with the amplitude of the second order sideband signals.
4. optical line terminal according to claim 1, it is characterised in that the light separator includes：
- Mach-Zehnder delay interferometer, with an input port and two output ends, wherein,
First output end is coupled to the optical selector, and the centre wavelength of the transmission spectrum of first output end matches each respectively
The wavelength of one optical signal；
Second output end is coupled to the coupler, and the centre wavelength of the transmission spectrum of second output end is matched and each respectively
The wavelength of two optical signals.
5. optical line terminal according to claim 1, it is characterised in that the Corticofugal Modulation of Somatosensory module includes Fabry-Perot
Sieve laser, the optical selector includes the second array waveguide grating, and the light separator, second array waveguide grating
And be connected between the coupler：
- first annular device, each first optical signal that the light separator is provided, being separated is supplied to second array
Waveguide optical grating, and by it is being multiplexed by second array waveguide grating, be reflected back be modulated with downlink information each first
Optical signal is supplied to the coupler.
6. optical line terminal according to claim 1 or 5, it is characterised in that in the dual wavelength maker and the light
It is also associated between separator：
- depolarizer, the polarization state for removing each first and second optical signal.
7. optical line terminal according to claim 1, it is characterised in that also include：
- uplink receiving module；
- the second circulator, is connected to the coupler, the output port of the optical line terminal and the uplink receiving module,
It is supplied to the output port to export the coupler coupled signal, and the upward signal that the output port is received is supplied to institute
State uplink receiving module.
8. a kind of optical communication system, including：
- the optical line terminal according to any one of claim 1-7；
- optical branching device, is connected with the optical line terminal；
- multiple optical network units, are connected with the optical branching device respectively, wherein each optical network unit includes such as bottom
Part：Light selecting module, for receiving optical signal, therefrom select it is corresponding to same seed photo-signal, different frequency first
The second optical signal in the first optical signal and second group of optical signal in group optical signal, and by the first and second optical signals phase
Mutually separate, wherein, first optical signal has been modulated downlink information, the not modulated signal of the second optical signal；It is descending
Receiving module, for being detected to first optical signal being separated, obtains the downlink information；Up modulation mould
Block, for second optical signal for being modulated to be separated by uplink information, and will have been modulated described in uplink information
Second optical signal is reflected back the smooth selecting module to export；
The downlink optical signal branch that the optical branching device provides the optical line terminal is to each optical network unit.
9. a kind of method of the transmission downstream signal in optic communication, comprises the following steps：
- seed photo-signal for the multiple different wave lengths being re-used is received, and respectively for each seed photo-signal, generate and the seed
First optical signal of the corresponding different wave length of optical signal is used as second group of optical signal as first group of optical signal and the second optical signal；
- will be multiplexed together corresponding to the first of each seed photo-signal group of optical signal, and by corresponding to the of each seed photo-signal
Two groups of optical signals are multiplexed together；
- each first optical signal is selected from first group of optical signal corresponding to each seed photo-signal；
- each first optical signal is corresponded respectively to, downlink information is modulated on first optical signal；
- each first optical signal for being modulated with downlink information is multiplexed with first group of optical signal；
- by the second group of optical signal being multiplexed together and be re-used, first group of light for having been modulated downlink information
Signal is coupled, and is exported.
10. method according to claim 9, it is characterised in that before described first group and second group of optical signal is separated,
Described first group and second group of optical signal are carried out solving the polarization state for removing the first group and second group optical signal partially.
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| CN105450325A (en) * | 2014-09-02 | 2016-03-30 | 上海贝尔股份有限公司 | Low-cost 40Gb/s symmetric TWDM-PON system |
| CN105763285B (en) * | 2016-04-21 | 2018-03-20 | 烽火通信科技股份有限公司 | The ONU and clock synchronizing method of TWDM PON systems |
| CN107437965B (en) * | 2016-05-25 | 2020-12-04 | 上海诺基亚贝尔股份有限公司 | Method and apparatus for supporting high-speed signal transmission in WDM-PON system |
| CN107121916B (en) * | 2017-07-11 | 2019-09-27 | 重庆理工大学 | Fiber waveguide device holography spectrometry method and device |
| WO2020069648A1 (en) * | 2018-10-02 | 2020-04-09 | Huawei Technologies Co., Ltd. | Transceiving with a predetermined frequency spacing |
| CN113938769B (en) * | 2020-06-29 | 2022-08-26 | 华为技术有限公司 | Power adjustment method, device and storage medium |
| CN115733553B (en) * | 2023-01-09 | 2023-04-18 | 之江实验室 | Reconfigurable optical engine emission system and fully-connected optical grid assembly therefor |
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